class_docstr: Base class for all DataFlow 
code: def size(self):
      return self.__len__()
  
imports: import threading
  from abc import ABCMeta, abstractmethod
  import six
  from ..utils.utils import get_rng
label_desc: Use image node_id 5 for calling the DataFlow obj's underlying member method code with example usage: obj.size() and returns: self